/**
 * Copyright 1996 self.com.au
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. (http://www.apache.org/licenses/LICENSE-2.0)
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed 
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for 
 * the specific language governing permissions and limitations under the License.
 *
 * <dhamma-message src="Atisha (11th century Tibetan Buddhist master)">
 * 	The greatest achievement is selflessness. The greatest worth is self-mastery.
 * 	The greatest quality is seeking to serve others. The greatest precept is continual awareness.
 * 	The greatest medicine is the emptiness of everything. The greatest action is not conforming with the worlds ways.
 * 	The greatest magic is transmuting the passions. The greatest generosity is non-attachment.
 * 	The greatest goodness is a peaceful mind. The greatest patience is humility.
 * 	The greatest effort is not concerned with results. The greatest meditation is a mind that lets go.
 * 	The greatest wisdom is seeing through appearances. 
 * </dhamma-message>
 *
 * @author Ashin Wimalajeewa
 *
 * Note, this is a very old runtime library that I have evolved since 1996. I rarely use it
 * now because the Apache Commons project has made it obsolete.
 */
package self.math.geom;

import java.awt.*;
import self.math.*;

final public class EllipseUtils {
  static public void getEllipseCentrePointIntersections( Rectangle r, double x, double y, double[] xyPoints ) {
    float a = r.width/2;
    float b = r.height/2;
    float xCentre = a + r.x;
    float yCentre = b + r.y;
    LinearEquation fromToCentre = new LinearEquation( x, y, xCentre, yCentre );
    EllipseEquation figEquation = new EllipseEquation( a, b, xCentre, yCentre );
    
    double[] xy2Sets = new double[4];
    if ( figEquation.getIntersectingPoints(fromToCentre, xy2Sets) ) {
      Point findClosestTo = new Point( (int)x, (int)y );
      if ( findClosestTo.distance(xy2Sets[0], xy2Sets[1]) < 
           findClosestTo.distance(xy2Sets[2], xy2Sets[3]) ) {
        xyPoints[0] = xy2Sets[0];
        xyPoints[1] = xy2Sets[1];
      } else {
        xyPoints[0] = xy2Sets[2];
        xyPoints[1] = xy2Sets[3];
      }
    }
  }
}